| abstract |
A quinolone carboxylic acid derivative having the following formula (1), <IMAGE> (1) wherein R1 is a hydrogen atom, an alkyl group, an aralkyl group, an ester residual group which can be hydrolyzed in living bodies, R2 is a hydrogen atom or an amino group which may be substituted by one or two lower alkyl groups, X is a hydrogen atom or a halogen atom, Y is CH2, O, S, SO, SO2, or N-R3, wherein R3 is a hydrogen atom or a lower alkyl group, and Z is an oxygen atom or two hydrogen atoms; or a salt thereof; and an antimicrobial agent comprising the same. The compound exhibits a superior antimicrobial activity, especially against gram positive microorganisms, and is thus useful for the treatments and prevention of various infectious diseases in clinics. |